A fuel feed apparatus includes a sub-tank received in a fuel tank, a fuel pump received in the sub-tank to supply fuel in the fuel tank to the outside of the fuel tank through the sub-tank, and a jet pump unit to supply fuel in the fuel tank into the sub-tank.
The jet pump unit includes a jet nozzle to generate suction power within the jet pump unit, a throat pipe communicated with the inside of the sub-tank, and a suction port to connect the throat pipe and the outside of the sub-tank. In this structure, fuel is jetted from the jet nozzle toward the throat pipe so that suction power is generated within the jet pump. Thus, fuel in the fuel tank is suctioned from the fuel tank into the sub-tank through the suction port and the throat pipe.
A fuel feed apparatus disclosed in JP-A-2004-108380, JP-A-2001-3826 and JP-A-2003-536006 has a jet pump unit to supply fuel in the fuel tank into the sub-tank, which is combined with a fuel pump. However, with this structure, when the specifications of the jet pump unit are altered, the structure of the fuel pump must be altered.
Furthermore, a fuel feed apparatus disclosed in JP-A-2001-207929 and JP-A-2005-351170 has a jet pump unit that is formed integrally with a sub-tank by using resin. However, with this structure, when the specifications of the jet pump unit are altered, the structure of the sub-tank must be altered.
Thus, the fuel pump and the sub-tank of the fuel feed apparatus cannot be standardized due to varying specifications of the jet pump unit.
Moreover, the jet nozzle of the jet pump unit of the fuel feed apparatus disclosed in JP-A-2001-207929 is provided on the lower side of the jet pump unit, and jets fuel upward. The suction port is formed on the lower side of the sub-tank. The outlet port of the throat pipe is opened upward, and is positioned on the upper side of the sub-tank. Fuel in the fuel tank is drawn into the sub-tank through the suction port and the outlet port of the throat pipe.
In this structure, fuel is discharged from the outlet port in all circumferential directions of the outlet port. In this case, when the outlet port of the jet pump unit is provided near the upper edge of the sub-tank, part of fuel discharged from the outlet port flows outside of the sub-tank. Therefore, the outlet port must be positioned below the upper edge of the sub-tank, so as to prevent part of the fuel discharged from the outlet port from flowing outside of the sub-tank.
Consequently, when the fuel pump is stopped, fuel in the sub-tank flows into the outlet port, and flows out of the sub-tank through the throat pipe and the suction port. This outflow of fuel will stop when fuel level in the sub-tank is the same level as the outlet port. Accordingly, the higher the outlet port is positioned in the sub-tank, the higher the fuel level in the sub-tank can be after the fuel pump stops, and the more fuel can be stored within the sub-tank. On the other hand, the lower the outlet port of the throat pipe is positioned in the sub-tank, the lower the fuel level in the sub-tank will be after the fuel pump is stopped, and a lesser amount of fuel will be stored within the sub-tank.
Considering this point, in the structure that the height of the outlet port of the jet pump unit is restricted, as disclosed in JP-A-2001-207929, it is difficult to store more amount of fuel within the sub-tank once the fuel pump has stopped.
In another case, a fuel feed apparatus received in a fuel tank that includes a plurality of tank sections (e.g. saddle-shaped fuel tank) is disclosed in JP-A-2004-316567. The fuel feed apparatus disclosed in JP-A-2004-316567 has a sub-tank that includes two jet pumps, a suction jet pump to draw fuel in one tank section into the sub-tank and a transfer jet pump to draw fuel in other tank section into the sub-tank.
In this structure, the jet nozzle of the transfer jet pump unit of the fuel feed apparatus is provided on the upper side of the transfer jet pump unit, and jets fuel downward. In this structure, a passage to supply fuel to the jet nozzle must be arranged above the jet nozzle, parallel to the transfer jet pump body. Thus, the transfer jet pump unit accounts for a larger portion of the inner volume of the sub-tank. Therefore, it is difficult to receive two jet pump units, the suction jet pump unit and the transfer jet pump unit, within the sub-tank. In this case, when two jet pump units must be received within the sub-tank, the amount of fuel that the sub-tank can store is reduced by the volume of the two jet pump units.